git rebase challenge build helper

build.rb

#!/usr/bin/env ruby

@authors = {
  "david" => "David S. Miller",
  "ingo" => "Ingo Molnar",
  "takashi" => "Takashi Iwai",
  "alexander" => "Al Viro",
  "russel" => "Russell King",
  "paul" => "Paul Mundt",
  "tejun" => "Tejun Heo",
  "thomas" => "Thomas Gleixner",
  "bartlomiej" => "Bartlomiej Zolnierkiewicz",
  "adrian" => "Adrian Bunk",
}

@file = "README"

n = File.readlines("origin/#{@file}").size

def random_text(length = 14)
  chars = ('a'..'z').to_a + ('A'..'Z').to_a
  (0..length).map { chars[rand(chars.size)] }.join
end

@authors.each do |nick, name|

  ENV['GIT_AUTHOR_NAME'] = "#{name}"
  ENV['GIT_AUTHOR_EMAIL'] = "#{nick}@foobar.com"

  system "git clone origin #{nick}"
  Dir.chdir(nick)

  (1..10).each do |e|

    branch_n = rand(e)
    branch = branch_n > 0 ? "branch_%s" % branch_n : "master"
    system "git checkout -b branch_%s %s" % [e, branch]

    (1..2).each do |r|
      case rand(3)
      when 0
        cmd = '%dd' % [rand(n) + 1]
      when 1
        cmd = '%di %s' % [rand(n) + 1, random_text()]
      when 2
        i = rand(n - 1) + 1
        o = rand(n - i) + i + 1
        cmd = '%d{h;d};%dg' % [i, o]
      end

      system "sed -i -e '#{cmd}' #{@file}"
      system "git commit -q -a -m 'Random change %s'" % [random_text()]
    end
  end

  Dir.chdir("..")
end

ENV.delete('GIT_AUTHOR_NAME')
ENV.delete('GIT_AUTHOR_EMAIL')

system "git clone -q origin mine"

Dir.chdir("mine")
@authors.each do |nick, name|
  next if nick == "adrian"
  system "git remote add #{nick} ../#{nick}"
end
Dir.chdir("..")

puts @authors.keys.map { |e| "#{e}/branch_%s" % [rand(10) + 1] }.join(" ")